Hunter, who lectures in health protection at the University of East Anglia, said: “As with any disease, it’s a real worry that it mutates and become untreatable.”

He told the Daily Star: “If it reaches the UK, Europe or the US it would be similar to the Ebola outbreak.

“We would probably have a few isolated cases but it shouldn’t spread like it has in Madagascar.”

Two thirds of the cases have been reported as pneumonic which is the most lethal strain.

Dr Charlotte Ndiaye, who works for the World Health Organisation in Madagascar, said: “WHO is concerned that plague could spread further because it is already present in several cities and this is the start of the epidemic season, which usually runs from September to April.”

The disease can be spread by coughing, sneezing, spitting and through contact with other fluids.

It is related to the Black Death which killed around 200 million people in Europe and Asia between 1346 and 1353.